The invention relates to a device for supplying fresh air to a turbocharged piston internal combustion engine having a fresh gas line section as an intake manifold which has an adjustable flap, a first end port for flowing in and a second end port for flowing out, between which ports a pivotably mounted shaft for the adjustable flap is provided in the tubular wall, said flap being coupled to an adjustment device for the purpose of adjustment, a compressed air port with an opening leading into the tubular interior between the flap and the second end port.
In addition, the invention also relates to a method for operating such a device for supplying fresh air to the turbocharged engine.
It is a known property of piston internal combustion engine with turbocharging that when the throttle is opened in the vehicle, the engine reacts with a certain degree of delay because the turbocharger can increase the supplied air quantity only slowly, which is known as a turbolag in the torque profile.
German Patent Document DE-PS-39 06 312 discloses a method and structure for reducing or shortening the turbolag, in which case, while the diesel engine is accelerating, a specific quantity of air is blown into the intake manifold from a compressed air accumulator. The fuel injection quantity is adapted accordingly. The turbocharged diesel engine is suitable particularly for use in commercial vehicles, such as city buses with an automatic transmission and compressed air brake system. The city buses perform a certain travel cycle by being able to predict the load and the rotational speed process of the diesel engine precisely, and in this way the blow-in time and the air quantity can be predetermined. The conditions of use for utility motor vehicles which are used in long distance traffic are quite different. These vehicles do not have any regular travel cycles and the payload varies within wide limits. Also, the driving style of the driver can exhibit large differences. The above structure and method are not well suited to address these problems.
The embodiments of the present invention provide a device and a method with which the blowing in of air can be adapted to the driving style and payload of the vehicle. At the same time the device can be installed or retrofitted as one mounted unit in various fresh gas line systems of diesel engines.
One advantage of the invention results from the fact that a flap in the fresh gas line is activated under electronic control, that is to say not only automatically by the fresh gas pressure, as is done conventionally, and that the activation is determined and processed electronically by the control unit, specifically as a function of the fresh gas pressure and also of other engine parameters.
According to an exemplary embodiment of the invention, the compressed air port is provided with a quantity regulating device which has a valve having a blocked position and any desired number of opened positions, and the quantity regulating device also has an electric/electronic input which is connected to the output of an electronic control unit, the input of the adjusting device of the flap being connected to the second output of the electronic control unit, so that the fully opened position of the flap is assigned a fully blocked position of the quantity regulating device. For example, an electronic control unit may control the position of the flap and of the quantity regulating device of the blown-in air. When the flap is commanded to the fully open position, the programming of the control unit may command the quantity regulating device to the fully blocked position. In other cases, intermediate positions of either or both devices may be commanded by the control unit.
The following exemplary outputs are preferably connected to the inputs of the electronic control unit according to this embodiment: output of the first pressure pickup whose pressure meter is arranged in the tubular interior between the flap and the first end port for flowing in and output of the second pressure pickup whose pressure meter is arranged in the tubular interior between the flap and the second end port for flowing out.
According to one advantageous exemplary embodiment of the invention, in the electronic control unit, the torque request signal can originate from one or more of the following sources: accelerator pedal, traction controller, cruise controller, electric stability program, driving assistance system or other systems which feed an external torque request to the engine control system.
According to another advantageous exemplary embodiment of the invention, the adjustment device of the flap also includes a position determining sensor for direct activation by the electronic control unit.
The exemplary embodiments of the invention also include a method for improving the acceleration behavior and emission behavior of a vehicle piston internal combustion engine, in particular of a diesel engine with turbocharging. A device is provided which has the purpose of supplying fresh air, and includes a compressed air accumulator in which compressed air is stored to be blown, in a regulated, temporary fashion, into the intake of the engine cylinder.
According to an exemplary embodiment of the invention, the method contains the following method steps:
determination of the torque request signal and feeding of the data to the electronic control unit,
determination of the engine characteristic values and feeding of the values to the electronic control unit,
determination of the position of the flap and feeding of the values to the electronic control unit,
determination of the air pressure in the interior of the fresh gas line section between the first end port and flap or second end port and flap and feeding of the pressure values to the electronic control unit,
determination of the air pressure in the interior of the intake line between the cylinder inlet valve and flap and feeding of the pressure value to the electronic control unit, as well as determination of the air pressure in the interior of the intake line between the flap and turbocompressor, and feeding of the pressure value to the electronic control unit,
processing of the abovementioned data and the measured values in the electronic control unit in order to produce activation output signals for opening/closing the compressed air valve for the temporary blowing into the intake line,
and simultaneous activation of the flap in the closing direction at the start of the blowing in process and in the opening direction at the end of the blowing in process.
According to one advantageous exemplary embodiment of the method, the following additional method steps may be carried out:
determination of the average frequency of the driver's request for acceleration by the software in the control unit, regulation of the blowing in of air and activation of the flap in an adaptive fashion with respect to the determined average frequency of the driver's request so that the air consumption is kept within certain limits but without an abrupt change in the duration of the air blowing in process.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.